Burner control



1966 w. A. BIERMANN ETAL 3,235,232

BURNER CONTROL Filed May 31, 1963 2 Sheets-Sheet 1 IN \"ENTORS Wiilium A.B iermonn Allen L.Te|chert FIG. W

1956 w. A. BIERMANN ETAL 3,235,282

BURNER CONTROL Filed May 31, 1963 2 Sheets-Sheet 2 Thermostat 60 64 l I Overheol Swilch aJ Stun 24v l IZOv Switches 9 r L Cemrlfugul 82 Switch -80 Flame \g: Prover ae Metering 70 Valve u 52 It] Slow Thermol Relay 78 I 2- j lv Z Fun Ignner Thermostat I22 overhear Swatch 66 92 as 72\ ue 24v "lZOv Switches r L I Flame ol PIOVGL J 78 T Ignller 3 INVENTORS G 3 76 William A.Blermonn 62 Allen L.Teicherl Attorney United States Patent 3,236,282 BURNER CUNTROL William A. Biermann, Broolcfield, and Allen L. Teichert, Menomonee Falls, Wis, assignors to Controls Company of America, Melrose Park, BL, a corporation of Delaware Filed May 31, 1963, Ser. No. 284,631 12 Claims. (Cl. 158-28) This invention relates to improved oil flow control valves of the type adapted to meter oil for the delivery to a burner.

Valves of this type are basically comprised of a casing having an inlet and a metering valve wherein the quantity of oil metered for delivery to the burner is dependent upon the head across the metering valve. The control valves known heretofore employ a bimetal to maintain the inlet valve closed until a satisfactory burner temperature is reached, and once this temperature is attained, a heating element is energized which in turn causes the hirnetal to warp out of the inlet valve closing position. Upon a drop in the burner temperature, the heating element is de-energized causing the bimetal to move to the valve closing position. These valves are rendered responsive to the combustion air conditions by various means which pneumatically relay the burner or draft pressure to the valve to render the same operable only at times of satisfactory combustion air conditions.

The principal object of this invention is to provide an oil fiow control valve which will have better response characteristics, both to a thermostat, as well as to the burner temperature and combustion air conditions than similar valves known heretofore.

This object is attained by providing a new control circuit for the control valve. To obtain better response to the thermostat, the control circuit is provided with means which cause only initial energization of the control circuit upon the closing of a thermostat, which, however, thereafter maintains the control circuit energized independently of the thermostat until the burner has reached a satisfactory temperature, at which time the control circuit is again returned to the control of the thermostat. The principal advantage gained by this feature is that frequent and rapid closing and opening of the thermostat (as is sometimes caused by vibration of the thermostat) will not result in the mere repeated initiation of the burning cycle without permitting the flame to reach a temperature at which the inlet valve is opened. Under such conditions, the control valves known heretofore were drained of their oil supply and were rendered inoperative until they were manually refilled.

The better response to burner temperature is attained by employing a solenoid which is energized in response to a flame prover to open the inlet valve at the instant when the flame prover indicates a satisfactory burner temperature. This feature, in particular, permits a faster high fire delivery to the burner if a new demand is called for by the thermostat right after the previous demand has been satisfied. Under these conditions the burner is still hot and, thus, the inlet valve is immediately opened as the new demand arises. In the previously known control valves, the inlet valve was only opened after its opening bimetal had again been sufficiently reheated to warp and permit the inlet valve to open. The thermo-cycling (reheating of the bimetal) is particularly time consuming when installing or servicing the valve, at which time its frequent actuation is required.

The improved response to the combustion air is attained by providing air proving means which will ener- 3,235,232 Patented Feb. 22, 1966 gize (or de-energize) the circuit elements controlling the metering valve, thereby rendering the control circuit directly responsive to the combustion air conditions.

Further, the control circuit embodying the present invention incorporates means operative to maintain a fire and proper amount of combustion air in the burner after the control valve has ceased to deliver oil thereto, thereby permitting the oil delivered prior to the closing of the control valve to be fully burned out. This feature eliminates a smoky shutdown of the burner experienced with controls used heretofore.

In view of the above, a further object of this invention is to provide a control circuit as described above which will eliminate smoky shutdowns of the burner.

Other objects and advantages will be pointed out in, or be apparent from, the specification and claims, as will obvious modifications of the two embodiments shown in the drawings, in which:

FIG. 1 is a vertical section through a constant level oil flow control valve showing solenoid responsive inlet and metering valves;

FIG. 2 is a diagram of the control circuit embodying the present invention schematically showing the inlet and metering valves;

FIG. 3 is a modified version of the control circuit shown in FIG. 2; and

FIG. 4 is a detail view of the metering valve solenoid.

Referring to the drawings in detail, FIG. 1 shows a constant level oil flow control valve having a housing 10 with an inlet 12 and an outlet 14, wherein the flow of oil into the housing is controlled by an inlet valve 16 and wherein the oil is metered for delivery to the burner (not shown) by means of a metering valve 18.

The inlet valve is comprised of valve stem 20 which is biased to the open position by spring 22 and controlled by fioat 24 to control the oil level in the casing. A sleeve 26 is pressed on the valve stem and is threaded to receive a nut 28 hearing on a valve guide member 30. A spring cup 32 seats on the flange of the sleeve 26 and an expansion spring 34 seats between the guide and the spring cup to co-act with the nut 28 in resiliently holding the nut, the guide and the spring cup in position. The float is pivoted at 36 and has ends (not shown) of lever 38 hearing against the washer plate 40 to cause a downward closing movement of inlet valve 16 upon the increase of the oil level in the housing 10, and to permit an upward movement of the valve upon a decrease of the oil level. The more detailed description of the inlet valve construction and its advantages are known from the US. patent of Bierrnann et al., Patent No. 2,581,901.

Further, the actuation of the inlet valve is controlled by the lever 42 which is pivotally secured to the housing at 44 and biased in an upward direction by spring 45, and by the striker plate 46 which is adapted to cooperate with arm 48 and auxiliary float 50 to close the inlet valve 16 upon occurrence of an excessive level of oil in the control valve. The cooperation between these parts is fully disclosed in the US. patent issued to Biermann et al., Patent No. 2,930,388.

The metering valve is comprised of a metering stem 52 which is biased in the upward direction by spring 54 thereby exposing metering slot 56 beyond the metering bore 58 of the valve guide 60 which cooperate to meter oil for delivery to the burner in accordance with the exposure of the metering slot beyond the metering bore. The amount of upward travel of the metering stern may be limited by suitable stop means well known in the art and for the sake of simplicity not shown in FIG. 1.

The above described structure does not form a part of this invention in itself, but is only novel in combination with the control circuits as illustrated in FIGS. 2 and '3. FIG. 2 shows the control circuit when it is de-energized and when the burner is relatively cool. The circuit is comprised of a low voltage side 60 (24 volts) and a high voltage side 62 (120 volts). Bimetal 64 is part of a thermostat which is adapted to control the temperature at the point distance from the control valve. The bimetal is warped to a circuit closing position to indicate a demand for heat, thereby passing current through conductor 66 to energize the fast thermal relay 68 and the slow thermal relay 70. After a very short time the fast thermal relay closes, thereby providing a bypass circuit 72 for the bimetal 64. It is apparent that as long as relay 68 remains closed, the low voltage circuit 60 remains energized regardless of the position of the bimetal 64. After the closing of the relay, slow thermal relay 70 closes, thereby energizing burner fan 76 and igniter 78 of the burner. The rotation of fan 76 in turn closes its centrifugal switch 80, thereby actuating metering valve solenoid 82 which attracts solenoid lever 84 causing it to pivot in opposition to the bias of spring 86 and thereby to lift arm 88 upwardly and away from the closing position (shown in FIG. 1) of the metering valve. When the arm 88 is removed from the metering stem 52, spring 54 biases the stem upwardly and permits oil to pass through metering slot 56 for delivery to the burner where igniter 78 is operable to ignite the same. After the oil has been ignited and after suflicient oil has been supplied to provide a proper burner temperature, flame prover 90 transfers from cold contact 92 to hot contact 94, thereby deenergizing fast thermal relay 68 and energizing inlet valve solenoid 96. Within a short time (about seconds) after deenergization relay 68 opens and returns the low voltage circuit to the control of the thermostat. As the flame prover transfers from the cold to the hot contact the solenoid 96 is energized and attracts its solenoid lever 98 in opposition to the bias of spring 100, thereby pivoting its arm 110 away from lever 42 and causing lever 42 to be biased away from valve stem thereby permitting the inlet valve 16 to be controlled by the float 24. With the inlet valve and metering stem in the open position, the control valve and burner are in high fire operation.

Should the bimetal 64 still be closed after circuit 72 is opened (as would be the case under most conditions), the high fire operation will continue until suflicient heat has been supplied to cause bimetal 64 to warp to a circuit open position. At this time the inlet valve and metering valve solenoids 96 and 82 are de-energized, causing their respective solenoid levers to be pivoted in response to springs 100 and 86 respectively and causing arm 88 to move the metering stem to a closed position and arm 110 to engage lever 42 and move the same against inlet valve 16 to retain the same in the closed position. Although the low voltage circuit is de-energized, the slow thermal relay remains closed for approximately one to two minutes, thereby maintaining fan 76 and igniter 78 energized after the metering valve 18 has closed. This delay feature permits a complete combustion of the oil delivered to the burner. Within a relatively short period after the flame in the burner has been extinguished, the flame prover will cool and move from hot contact 94 to cold contact 92. This time is approximately four minutes.

Should the thermostat call for a new demand of heat within a very short period after the low voltage circuit 60 has been de-energized, the flame prover will still be on hot contact 94 and the relay 70 will still be closed, thereby maintaining fan 76 and igniter 78 energized. In this condition, the inlet valve solenoid 96 and the metering valve solenoid 82 will be immediately actuated and cause the immediate opening of the metering valve and render the inlet valve responsive to float 24, thus returning the control valve and burner to the high fire position.

Should the thermostat 64 call for a new demand of heat within approximately four minutes after the de-energization of low voltage circuit 60, the flame prover will still be in engagement with hot contact 94, however the bypass circuit 72 will have been de-energized. In this condition the inlet valve solenoid 96 will be immediately energized and the high voltage circuit 62 and metering stem solenoid 82 will be energized in the sequence described above.

The circuit illustrated in FIG. 3 is identical to that of FIG. 2 except that a switch 112 is provided between conductor 66 and the metering stem solenoid 82. The switch connects metering valve solenoid 82 through cold contact 92 of the flame prover and is adapted to be moved upon energization of the solenoid to engage contact 114. The purpose of switch 112 is to prevent actuation of the metering solenoid while the flame prover still is on hot contact 94. The only purpose for this feature is to guard against a condition in which the flame prover switch has become welded to hot contact 94, thereby always indicating a hot condition regardless of the actual state of the burner. In the case when the flame prover of the circuit shown in FIG. 2 becomes welded to the hot contact the inlet valve will always be immediately open upon energization of the low voltage circuit 60 regardless of the actual state of the burner, thereby permitting the burner to start up under high fire conditions and causing an over supply of oil in the burner. The over supply of oil at the start results in a smoky fire. Switch 112 of the circuit shown in FIG. 3 eliminates this, since the flame prover must always be on the cold contact to initiate energization of the metering stem solenoid. In turn, the circuit of FIG. 3 will not be capable of the quick response upon fast recycling of the thermostat, since the flame prover will always have to cool down before the control valve may be again re-actuated.

Both circuits are provided with normally closed switches 116 and 118 whereby switch 118 may be moved to engage contact 120 and switch 116 may be simultaneously moved to an open position thereby supplying current to the inlet valve solenoid to open the inlet valve. The principal purpose of this is to permit filling of the casing 10 upon installation or after repair without permitting flow to the burner. Both circuits are also pro= vided with switch 122 which is adapted to be automatically opened upon overheating of the burner.

In summary, it is important to note that the relays 68 and 70 are not to be limited to the thermal type, but that relay 68 could also be an electromagnetic relay which does not have the time delay feature and that slow thermal relay 70 could be a relay which is operable to move switch 74 to the closed position upon its immediate energization, and to delay the opening of switch 74 for the time span required to fully burn out the oil in the burner after closing of the metering valve 18. Relay 68 ispreferably of the fast thermal type, because it closes and opens Without any of the noises associated With electromagnetic relays. Also, the actuation time of fifteen seconds or so does assure that the inlet valve solenoid will be always energized for a time period even if the bimetal has opened by the time the flame prover indicates a hot flame. The slow thermal relay 70 is important only when shutting down the burner to provide the time delay necessary for a full burnout of the oil in the burner. It serves no important function in delaying the actuation of the metering stem and of the ignition and fan at the initiation of the burn-ing cycle. However, from a cost standpoint, the delay at the initiation of the burning cycle is not thought detrimental to the operation of the control valve and is further thought justified from cost standpoint if compared to a relay which would close without a time delay, but would open with the required delay.

Although but two embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

We claim:

1. A burner control system for metering fuel for delivery to a burner, comprising:

a thermostat switch operable to indicate a heat demand;

a reservoir casing having an inlet and an outlet;

a valve for said inlet and a valve for said outlet;

first electrical valve control means electrically operable to control movement of said inlet valve;

second electrical valve control means electrically operable to control movement of said outlet valve and cooperating with said first valve control means to control fuel flow through said casing;

a control circuit including circuit means connected to said first and second electrical valve control means to render said control means respectively operative and inoperative when said control circuit is energized and de-energized;

said control circuit being energized in response to the indication of a demand by said thermostat switch;

said control circuit having shunt circuit means including switch means which is operable to close in response to said indication of demand to thereby shunt said thermostat switch and to cause said control circuit to remain energized independent of said thermostat switch; and

a flame prover including switch means operable to be actuated in response to the indication of a satisfactory burning temperature in the burner, said shunt circuit means being responsive to the said actuation of said flame prover switch means to return said control circuit to be controlled by the thermostat switch.

2. A fuel flow control system including a control device having a reservoir casing with inlet and outlet valves which cooperate to meter fuel for delivery to a burner and including flame proving switch means and air proving switch means, the switch means being actua'ble to indicate burner temperature and combustion air supply respectively, comprising in combination:

a thermostat switch operable to indicate a heat demand;

first valve control including actuating means operable to open the inlet valve when the fuel level in the casing is below a predetermined level and including a solenoid mechanically connected to said inlet valve and operable when energized to render said valve responsive to said actuating means and when deenergized to close said inlet valve and render said actuating means ineffective;

second valve control including actuating means operable to open the outlet valve to an open position for metering fuel for delivery to the burner and including a solenoid mechanically connected to said outlet valve and operable when energized to render said valve responsive to said actuating means and when tie-energized to close said outlet valve and render said actuating means ineffective;

circuit means connecting said inlet valve solenoid to the flame proving switch means and operable to energize said inlet valve solenoid in response to the flame proving switch means indicating a satisfactory burner temperature and to de-energize said inlet valve solenoid in response to the flame proving switch means indicating a lower than satisfactory burner temperature; and

circuit means connecting said outlet valve solenoid to said air proving switch means and being operable to energize said outlet valve solenoid in response to actuation of the air proving switch means at a satisfactory air supply, and being operable to de-energize said outlet valve solenoid when said air proving switch means indicates a lower than satisfactory air supply.

3. A control system including a constant level fuel control device having a reservoir casing with an inlet and an outlet valve which cooperate to meter fuel for delivery to a burner in response to the indication of a heat demand, comprising in combination:

a thermostat switch operable to close and thereby indicate a heat demand;

solenoid means operable when de-energized to close the inlet valve, and when energized to render the inlet valve movable in accordance with the fuel level in the casing;

solenoid means operable when tie-energized to close the outlet valve, and when energized to render the outlet valve movable to an open position for delivery of fuel to the burner;

flame proving switch means adapted to be actuated at a satisfactory burner temperature to indicate such temperature in the burner;

first circuit means connecting the outlet valve solenoid means for energization in response to the indication of a demand by the thermostat switch to thereby cause delivery of the fuel when said demand is indicated;

second circuit means connecting the inlet valve solenoid means for ene-rgization in response to closing of said thermostat switch when the flame proving switch means indicates a satisfactory burner temperature thereby permitting said solenoid means to render the inlet valve capable of providing immediate fuel flow into the casing if the demand comes when the burner is at the satisfactory temperature, and causing a delay of the fuel flow into the casing until the indication of said satisfactory burner temperature when said thermostat switch closes at a time when said flame proving switch means indicates a burner temperature below said satisfactory temperature.

4. The combination of claim 3 having shunt circuit means including switch means which closes in response to the indication of a demand by the thermostat switch to thereby connect said shunt circuit means for shunting the thermostat switch, said shunt circuit switch being connected to energize said first circuit means when said switch closes, and said flame proving switch being connected to open said shunt circuit in response to the actuation of said flame proving switch indicating said satisfactory temperature.

5. A control device according to claim 4 having switch means which is responsive to the indication of said demand to energize an ignition circuit for the burner.

6. A control device according to claim 5 wherein said last mentioned switch means is connected to actuate air supply means for supplying combustion air to the burner.

7. A control device according to claim 6 wherein said last mentioned switch means is operable .to maintain said air supply means energized for a time interval after the inlet valve has been closed to thereby permit complete combustion of the oil delivered to the burner.

8. A control system for mete-ring fuel for delivery to a burner, comprising:

a thermostat switch operable to indicate a heat demand;

a reservoir casing having an inlet and an outlet;

an inlet valve and an outlet valve;

electrical valve control means operable when energized to control movement of said inlet valve and cooperating with control means for said outlet valve to control fuel flow through said casing;

a cont-r01 circuit including temperature responsive switch means operable to move from one position to a second position in response to rise in burner temperature to a level indicating satisfactory burning and to move from said second to said first position in response to a drop in said burner temperature below said level, said control circuit also including shunt circuit means which includes switch means operable to close and thereby cause said circuit means to shunt said thermostat switch in response to the indication of said demand, said temperature responsive switch means being connected to said electrical valve control means to energize said electrical valve control means when moving from said first to said second position and being connected to close said shunt circuit means when said temperature responsive switch means is in said first position and to open said shunt circuit means when moving from said first to said second position to thereby return said control circuit to the control of said thermostat switch at said temperature level.

9. A control system according to claim 8 wherein said control circuit also includes time delay means operable to delay the de-energ-ization of said shunt circuit means until after said electrical valve control means has been energized.

10. A control system according to claim 9 wherein said control means for said outlet valve is electrically actuable, and where-in said control means is connected in said control circuit for energization and de-energization with the energization and de-energization of said control circuit respectively.

11. A control system according to claim 10 wherein each of said valve control means includes a solenoid which is mechanically connected for closing the corresponding valve in response to energization of the solenoid.

12. A control system according to claim 11 having a switch movable from one position to another in response to energization of said outlet valve solenoid means and connected to initially energize said outlet valve solenoid only When said flame proving means indicates a less than satisfactory temperature in the burner, and said switch being moved in response to said initial energization 'to connect said solenoid means for continued energization independent of said flame proving means.

References Cited by the Examiner UNITED STATES PATENTS 2,214,912 9/1940 Valjean 15828 2,237,041 4/ 1941 Schreuder 15 8-42.2 2,388,666 11/1945 Bower 158-28 2,582,827 1/1952 Gibson 158-28 FOREIGN PATENTS 883,815 12/1961 Great Britain.

JAMES W. WESTHAVER, Primary Examiner. 

1. A BURNER CONTROL SYSTEM FOR METERING FUEL FOR DELIVERY TO A BURNER, COMPRISING: A THERMOSTAT SWITCH OPERABLE TO INIDCATE A HEAT DEMAND; A RESERVOIR CASING HAVING AN INLET AND AN OUTLET; A VALVE FOR SAID INLET AND A VALVE FOR SAID OUTLET; FIRST ELECTRICAL VALVE CONTROL MEANS ELECTRICALLY OPERABLE TO CONTROL MOVEMENT OF SAID INLET VALVE; SECOND ELECTRICAL VALVE CONTROL MEANS ELECTRICALLY OPERABLE TO CONTROL MOVEMENT OF SAID OUTLET VALVE AND COOPERATING WITH SAID FIRST VALVE CONTROL MEANS TO CONTROL FUEL FLOW THROUGH SAID CASING; A CONTROL CIRCUIT INCLUDING CIRCUIT MEANS CONNECTED TO SAID FIRST AND SECOND ELECTRICAL VALVE CONTROL MEANS TO RENDER SAID CONTROL MEANS RESPECTIVELY OPERATIVE AND INOPERATIVE WHEN SAID CONTROL CIRCUIT IS ENERGIZED AND DE-ENERGIZED; SAID CONTROL CIRCUIT BEING ENERGIZED IN RESPONSE TO THE INDICATION OF A DEMAND BY SAID THERMOSTAT SWITCH; SAID CONTROL CIRCUIT HAVING SHUNT CIRCUIT MEANS INCLUDING SWITCH MEANS WHICH IS OPERABLE TO CLOSE IN RESPONSE TO SAID INDICATION OF DEMAND TO THEREBY SHUNT SAID THERMOSTAT SWITCH AND TO CAUSE SAID CONTROL CIRCUIT TO REMAIN ENERGIZED INDEPENDENT OF SAID THERMOSTAT SWITCH; AND A FLAME PROVER INCLUDING SWITCH MEANS OPERABLE TO BE ACTUATED IN RESPONSE TO THE INDICATION OF A SATISFACTORY BURNING TEMPERATURE IN THE BURNER, SAID SHUNT CIRCUIT MEANS BEING RESPONSIVE TO THE SAID ACTUATION OF SAID FLAME PROVER SWITCH MEANS TO RETURN SAID CONTROL CIRCUIT TO BE CONTROLLED BY THE THERMOSTAT SWITCH. 